I will give this a go with my car. Any detailed 'how to' pictures available?
After installing the walbro 400 hard wired, I was getting overrun. I had to install an afpr, but the lowest I could get the fuel pressure was between 47-49psi. This was enough to get a tune done, but have noticed when slowly driving around the afr hits 10.5.

 

[QUOTE=Aussie IX;10371680
After installing the walbro 400 hard wired, I was getting overrun.[/QUOTE]

The first post in this discussion explains how to fix that.

 

Thanks Ted B, just did this and fixed the problem. I was thinking that I might have to replace the return line all the way to the tank, but even then it wouldn't have worked with such a small orifice.



Orifice size before;



Orifice size after;

 

well my full blown still leaks. I adjusted the height of the pumps to get them right at or near the bottom of the tank and replaced the clamps and fittings. Worked much better.

I got the Epoxy from FB and have not yet put it in yet... should fix the leak.

however I still have a problem with the car running out of fuel at 3/8 tank. I think it may be getting stuck on the socks as Ted suggested.

When I take it out to fix the wire leak I'll take a look. I hate this thing. This will be the 6th time I've taken it out to fix problems associated with it. Not fun.

 

I may know your fuel level problem.

The fuel level signal is composed of two readings, the main (left) and sub (right) tank sending units in series. Basically, the circuit is a daisy-chained single wire affair that looks like this:

Power -> Gauge -> Sub level -> Main level -> Ground


The gauge is just an ammeter that registers current flow between the power source and ground, with the two level sensors acting as resistors in series.

If you've fiddled with the pump power and ground wiring, be sure you didn't accidentally ground the sub level sensor:

Power -> Gauge -> Sub level -> Ground -> Main level -> Ground


If you did (like we accidentally did), the premature ground effectively removes the main level sensor from the circuit, and causes the exact situation you're experiencing. The black 'ground' lead from the sub level sensor is connected to the red the power lead to the main level sensor. If you've inadvertently grounded the sub sensor, you won't like the result.

FYI

 

yeah... I have a wire that I grounded... however I think its for the 2nd pump. I'll double check the wiring when I take a look at it. That may very well be my issue. Thanks Ted!

 

So, what psi hobbs switch should i get?
Im builting a 2.4L with manley ibeam tt rod and manley 9:1 piston, and running on a pre 6266jb turbo. My engine is fully built from fpr and fuel rail to fic 2150cc injectors. I want to run on e85 on high boost and pump gas on low boost. I will have dual maps setting on a stock ecu. Hoping to make 700hp on it with between 35-40psi on e85.

Also would 2 walbro 255 would be enough for fuel for my setup?
And how would i know if someone is selling me a E85 safe Walbro 255? Can someone tell me a parts number for the Walbro 255 that is e85 compatibe?
I know that they make walbro 485 e85 safe now, but i just wanted to used a 2 walbro 255 if its enough fuel for me then its fine

Thank you for heping

 

Just wanted to say thank you to the OP and Aussie IX. Installed a Walbro/TI Automotive 416 lph pump (F90000267) last weekend. Also did the pressure release mod for extra flow. I run -6 lines and a fuel lab mini fpr and the pump was hardwired.

Couldn't get base pressure lower than 65psi and drove it around for a week until I could figure out a solution and stumbled upon this thread. To add further complication the pressure pushed the oring and pressure dropped to 30psi...from one extreme to the next!

Anyway, I elected to try a 3mm (1/8" for you imperial boys) bit first before going to 3.5mm and that did the trick preferctly. Dropped base down by 20psi to a nice 45psi and the fpr was able to do its thing. l'll report back on the gauge cluster as it approaches a 1/4 tank to see if that leaves enough vacuum to pull into the other tank. This was a life saver!

 

Even the 3.5mm causes no siphon issues, so if 3mm works fine, you're all good. It isn't often the fix for a difficult problem is so simple ... and free!

 

Do you think the 3.5mm hole will be enough for dual 450 running at on e returning the through a -8 line?

 

Yes.

 

I've followed this thread while looking for instructions for the Full Blown kit that I'm installing on a customers evo, I have both oem and FB out and if anyone needs any measurements I can do that. Also FYI in case you do mess up your venturi valve, Radium Engineering makes one that tunable.
https://www.radiumauto.com/Venturi-J...-Kit-P760.aspx

Tommy